In Fallout 4, the player character is able to rename any weapon, including unique weapons, at any weapons workbench. Renaming weapons does not affect any weapon stats. This primarily adds a level of personalizing to weapons and can help avoid accidentally disassembling a favored weapon.

Weapons may be modified in Fallout 4. Each weapon has modification 'slots' (e.g. barrel, grip, magazine, sights) that may be modified with increasingly powerful or useful mods by the player character based on their perks. However, the player character may salvage useful mods that are not yet available via the player character's perk level by simply modifying any weapon that already has the mod of interest.[1] By replacing the mod of interest with any available mod the original mod goes into inventory and may then be used to alter the player character's chosen weapon without regard for their perk level. Unique weapons do not offer this capability; their special mods are 'reserved' and since they are unique, no other examples are available to be salvaged.

If a player character puts unique and legendary weapons in a container in a settlement, nearby NPCs, like settlers or even enemy attackers, can randomly take them and they may be irretrievable. Therefore, access to personal containers should be restricted, either by obstructing the expected path used by them to reach the container, or by the use of powered doors, holes, floating structures, etc.